The effects of combination of methanolic leaf extract of Azadirachta indica and diminazene diaceturate in the treatment of experimental Trypanosoma brucei brucei infection in rats

Objective: To investigate the effects of combination therapy of methanolic leaf extract of Azadirachta indica (A. indica) and diminazene diaceturate (DDA) in the treatment of experimental Trypanosoma brucei brucei (T. brucei brucei) infection in rats. Methods: Acute toxicity study of the drug and extract combinations were done. Selection of the best drug and extract combinations was carried out using fifty four rats of both sexes separated into 9 groups. Three dose combinations were derived from selection of the best drug and extract combinations used for the final study viz: 7 mg/kg bw DDA plus 125 mg/kg bw extract (group B), 3.5 mg/kg bw DDA plus 250 mg/kg bw extract (group C), and 1.8 mg/kg bw DDA plus 500 mg/kg bw extract (group D). The final study had in addition to the three groups derived from the dose response study, four other groups viz: uninfected untreated negative control (group F), infected and treated with 3 000 mg/kg bw extract alone (group E), infected and treated with 7 mg/kg bw DDA alone (group A), and infected untreated positive control (group G). The parameters assessed were onset of parasitaemia (OP), level of parasitaemia (LOP), clearance of parasites post treatment (COPPT), relapse infection period (RIP), post infection survival period PIST. Results: There was no significant difference in OP between the groups (P<0.05). One day post treatment, the mean LOP of groups A, B, and C were found to be significantly lower than that of group D which in turn was lower than that of group E and C respectively. The mean LOP of group E was significantly lower than group C two clays post treatment and this trend continued throughout the experimental period. Mean COPPT of group D was significantly longer than that of groups A, C and B. There was no significant difference in the mean COPPT among groups B, C and A. The mean RIP of group D was significantly shorter than group C, and that of group C was significantly shorter than that of group A. There was no relapse of infection in group B. The PIST of group E did not differ significantly from group G. Conclusions: This experiment stands to conclude that combination of 125 mg/kg bw extract and 7 mg/kg bw BOA is very effective in the treatment of trypanosomosis, caused by T brucei. This combination therapy proved to be better than single therapy of DDA.